JP4381918B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker that can accurately detect the temperature of an object to be heated such as a pan on a top plate.

2. Description of the Related Art Conventionally, in this type of induction heating cooker, an infrared sensor is disposed on the lower surface of the top plate, and infrared rays from an object to be heated are detected through the top plate (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 3-184295

  However, in the conventional configuration, since the infrared radiation energy has a large difference between a low temperature of 100 ° C. or less and a high temperature of about 300 ° C., it is possible to detect a wide range of temperatures simply by placing an infrared sensor on the bottom surface of the top plate. In addition, there is a problem that an error occurs in the detected temperature because infrared radiation from the top plate is included.

  The present invention solves the above-mentioned conventional problems, can cope with a wide range of temperature detection, has no error in the detection temperature, and accurately detects the temperature of an object to be heated such as a pan on the top plate to control heating. An object of the present invention is to provide an induction heating cooker.

In order to solve the conventional problem, an induction heating cooker of the present invention includes a heating coil for heating an object to be heated, a top plate for placing the object to be heated on the heating coil and transmitting infrared rays, Infrared detection means for detecting infrared rays that are radiated from the object to be heated and transmitted through the top plate, and a first temperature detection for detecting the temperature of the object to be heated from the output of the infrared detection means Means, a second temperature detection means configured by a thermistor disposed on the lower surface of the top plate for detecting the temperature of the top plate, and a control means for controlling the power supplied to the heating coil, The temperature detecting means includes an output subtracting means for subtracting a voltage corresponding to the amount of infrared light in accordance with the temperature of the top plate detected by the second temperature detecting means from the output voltage of the infrared detecting means, and the output subtracting means Amplification to amplify the output And a stage, said control means in response to an output of said amplifying means is an induction heating cooker which controls the heating power to the heating coil, wherein the amplifying means have a switching means for switching the amplification factor The control means has an automatic cooking sequence, and in the heating mode in which the fried food is performed, the amplification factor is set so that a temperature change up to 350 ° C. can be detected in the temperature of the heated object, In the automatic cooking sequence for performing the cooking menu for cooking rice, the amplification factor is switched to be lower than that in the heating mode, and the temperature control of the automatic cooking sequence is performed.

Thereby, the temperature detection of the temperature range matched with the cooking menu can be performed accurately with high accuracy .

The induction heating cooker of the present invention can accurately and accurately detect the temperature in the temperature range that matches the cooking menu .

1st invention sets the gain of an amplification means so that a temperature change to 350 degreeC can be detected in the temperature of the to-be-heated object in the heating mode which performs a stir-fry, and the cooking menu of a kettle or rice cooking In the automatic sequence for performing cooking, the amplification factor is switched to a lower value than in the heating mode in which the stir-fried food is used, and the temperature control of the automatic cooking sequence is performed, thereby accurately detecting the temperature in the temperature range according to the cooking menu. It can be done with accuracy.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
FIGS. 1-5 shows the induction heating cooking appliance in Embodiment 1 of this invention.

  As shown in FIG. 1, the induction heating cooker in the present embodiment includes a heating coil 3 that heats a heated object 1 such as a pan, and a high-frequency current supplied to the heating coil 3 to cause the heated object 1 to be electromagnetically induced. An inverter 5 that generates heat, a top plate 2 on which the object to be heated 1 is placed above the heating coil 3, and an infrared detecting means that is disposed on the lower surface of the top plate 2 and detects infrared rays emitted from the bottom surface of the object to be heated 1. 6, first temperature detecting means 9 for detecting the bottom surface temperature of the object to be heated 1 from the output of the infrared detecting means 6, and second temperature detecting means for detecting the temperature of the top plate 2 disposed on the bottom surface of the top plate 2 10 and a control means 11 comprising a microcomputer for controlling the power supplied to the heating coil 3 in accordance with the outputs of the first and second temperature detection means 9 and 10. The infrared detecting means 6 is composed of a PIN photodiode (InGaAs) or the like, a cylindrical magnetic shield means 7 for preventing leakage magnetic flux from the heating coil 3 from passing through the infrared detecting means 6, and the object to be heated 1. And reflecting means 8 comprising a lens barrel that efficiently guides the infrared rays from the infrared rays to the infrared detecting means 6.

  As shown in FIG. 2, the first temperature detecting means 9 includes an output subtracting means 13 for subtracting the output of the infrared detecting means 6 in accordance with the output of the second temperature detecting means 10, and the output subtracting means. The control means 11 controls the heating output to the heating coil 3 according to the output of the amplifying means 12. The control unit 14 of the control unit 11 controls the degree of amplification of the output subtraction unit 13 and the amplification unit 12 based on information from the first temperature detection unit 9 and the second temperature detection unit 10, so that the object to be heated 1 The temperature is calculated and detected.

  In the induction heating cooker according to the present embodiment described above, when a power source (not shown) is turned on and a predetermined temperature is set with the operation switch, power is supplied from the inverter 5 to the heating coil 3 under the control of the control means 11. . When electric power is supplied to the heating coil 3, an induction magnetic field is generated in the heating coil 3, and the object to be heated 1 on the top plate 2 is induction heated. By this induction heating, the temperature of the object to be heated 1 rises, and the food in the object to be heated 1 is cooked.

  Here, the operation of the infrared detecting means 6 will be described. When the temperature of the article 1 to be heated rises, infrared rays corresponding to the temperature are emitted from the article 1 to be heated. In general, as shown in FIG. 3, the red radiant energy radiated from an object is determined by its temperature, and increases as the temperature increases and also expands to the short wavelength side. The top plate 2 in the induction heating cooker according to the present embodiment is made of glass ceramic or the like, and the glass ceramic can transmit 90% or more with respect to infrared rays having a wavelength range of 2.5 μm or less. When the temperature is higher than or equal to ° C., infrared radiation energy in a wavelength region of 2.5 μm or less is incident on the infrared detection means 6. Here, the infrared detecting means 6 is composed of a PIN photodiode (InGaAs) or the like that has a highly sensitive detection performance with respect to infrared rays in a wavelength range of 0.7 to 2.5 μm or less. With this PIN photodiode, an output current matching the temperature of the object to be heated 1 as shown in FIG. 4 is obtained. However, as shown in FIG. 4, the output current and the temperature of the heated object 1 are not linearly correlated. This is because the radiant energy increases rapidly as the temperature rises.

  Therefore, the amplification factor must be changed depending on the temperature range of temperature detection. This control will be described with reference to FIGS.

The second temperature detecting means 10 is composed of a thermistor or the like that is in contact with the top plate 2 through silicon oil or the like, and can detect the temperature of the top plate 2 in a range where infrared rays from the heated object 1 are transmitted. . The top plate 2 has a transmittance of about 90% for infrared rays in the wavelength region of 2.5 μm or less, but the remaining 10% radiates the temperature of the top plate 2 itself to the infrared detecting means 6. Become. As shown in FIG. 5, when the temperature of the top plate 2 is high, for example, 150 ° C., the temperature detection by the infrared detecting means 6 is greatly affected even by 10% radiant energy. In order to eliminate this influence, the output is subtracted by the output subtracting means 13 in accordance with the output of the second temperature detecting means 10. The subtracted output is amplified by the amplifying means 12 and input to the control unit 14 to calculate the detected temperature. In this case, since the influence of the top plate 2 that is a noise component is large, it is possible to detect the change of the infrared detecting means 6 corresponding to the temperature change of the heated object 1 with high resolution by subtracting before amplification. It becomes. Thereby, the influence of the temperature of the top plate 2 can be further reduced, and the temperature detection of the article 1 to be heated can be performed accurately.

  Here, the output subtracting means 13 subtracts the amount of infrared rays corresponding to the temperature of the top plate 2 as a voltage. However, if the temperature of the top plate 2 is within the temperature use range of the infrared detecting means 6, a heater or the like is used. The infrared detecting means 6 may be warmed. This is because if the top plate 2 and the infrared detecting means 6 are at the same temperature, the amount of infrared light is not transferred, and the amount of infrared light from the object to be heated 1 can be detected without being affected by the temperature of the top plate 2. is there.

  In the normal heating mode, the temperature of the object to be heated 1 is detected by lowering the amplification factor in order to detect changes up to 350 ° C. such as stir-fried food and prevention of overheating. The switching is performed by providing the amplifying means 12 with a gain switching means (not shown) in accordance with the cooking menu from the control unit 14. Since the temperature is low immediately after the start of heating, it is possible to increase the amplification factor and switch when the temperature rises. With this configuration, it is possible to accurately detect the temperature in the temperature range corresponding to the temperature state of the article 1 to be heated with high accuracy.

(Embodiment 2)
Next, the induction heating cooker in Embodiment 2 of this invention is demonstrated.

  The infrared detecting means 6 and the second temperature detecting means 10 shown in FIG. 1 are arranged at the center of the heating coil 3, and these are arranged between the inner and outer circumferences of the heating coil 3, that is, the lower surface of the top plate 2 at the intermediate point. , The temperature of the heated object 1 between the inner and outer circumferences of the heating coil 3 where the heated object 1 becomes the highest temperature is more responsive, particularly the temperature of the heated pot 1 in the pan and the pan in a state similar to the sky. It can be detected well.

  In addition, a reflection means 8 for condensing infrared rays and guiding the infrared detection means 6 to the infrared detection means 6, and a magnetic shield means 7 disposed outside the reflection means 8, the second temperature detection means 10 is disposed outside the magnetic shield means 7. By doing so, a configuration in which the magnetic shield means 7 is downsized is also possible, the influence of temperature rise due to the magnetic shield can be reduced, and the temperature of the heated object 1 can be stably detected by the infrared detection means 6 with higher accuracy. is there.

  Further, as shown in FIG. 6A, the second temperature detecting means 10 is arranged outside the reflecting means 8 that collects infrared rays and guides them to the infrared detecting means 6 and inside the magnetic shield means 7. In this way, more infrared rays can be collected and the temperature can be detected by the infrared detection means 6 and the second temperature detection means 10 without being affected by the magnetic field by the magnetic-shielding means 7, so that the accuracy can be improved. The temperature of the heated object 1 can be detected stably.

  Further, as shown in FIG. 6B, the magnetic-shielding means 7 has a non-circular cross-sectional shape (D-shape in the present embodiment), and the second temperature detection means 10 is disposed so as to face the notch 15. By doing so, since the range detected by the infrared detecting means 6 and the range of the top plate 2 detected by the second temperature detecting means 10 are closer to each other, the temperature of the heated object can be detected more accurately and stably. is there.

  Further, if the infrared detecting means 6 and the second temperature detecting means 10 are arranged at a position symmetrical with respect to the central axis of the heating coil 3, the temperature detecting position becomes the central axis of the article 1 to be heated. On the other hand, since the temperature can be detected at positions that are axially symmetric, the temperature of the object to be heated 1 can be detected more accurately and stably.

  Further, the control means 11 has an automatic cooking sequence. If the temperature control of the automatic cooking sequence is performed using the temperature information of the second temperature detection means 10, the temperature range corresponding to the cooking menu is set. Temperature detection can be performed accurately and with high accuracy. In addition, when it has an automatic sequence for performing cooking menus such as kettle and rice cooking, in order to detect temperatures in the range of 130 ° C. or lower, the amplification factor 12 is increased so that the region of 60 to 130 ° C. is a full range. What is necessary is just to detect.

  As described above, the induction heating cooker according to the present invention can cope with a wide range of temperature detection, has no error in the detected temperature, and accurately detects the temperature of an object to be heated such as a pan on the top plate. Therefore, it can be applied to various induction heating cookers such as general home use and business use.

The block diagram which shows the induction heating cooking appliance in Embodiment 1 of this invention Block diagram showing first and second temperature detection means and control means in the induction heating cooker Graph showing the distribution of infrared rays transmitted through the top plate and the sensitivity wavelength range of infrared detection means in the induction heating cooker The figure which shows the relationship between the output of the infrared detection means and temperature in the induction heating cooking appliance. Graph showing temperature detection data after correction in the same induction heating cooker (A) Plan view showing configuration examples of infrared detection means and second temperature detection means in Embodiment 2 of the present invention (b) Plan view showing another configuration example

DESCRIPTION OF SYMBOLS 1 Heated object 2 Top plate 3 Heating coil 6 Infrared detection means 7 Magnetic-shield means 8 Reflection means 9 1st temperature detection means 10 2nd temperature detection means 11 Control means 12 Amplification means 13 Output subtraction means 15 Notch part

Claims (1)

A heating coil for heating an object to be heated, a top plate for placing the object to be heated on the upper part of the heating coil and transmitting infrared rays, and a radiation plate disposed below the top plate and emitted from the object to be heated and transmitted through the top plate Infrared detecting means for detecting infrared rays to be detected, first temperature detecting means for detecting the temperature of the object to be heated from the output of the infrared detecting means, and a thermistor disposed on the lower surface of the top plate for detecting the temperature of the top plate And a second temperature detection unit configured to control the electric power supplied to the heating coil, and the first temperature detection unit detects the second temperature from the output voltage of the infrared detection unit. Output subtracting means for subtracting a voltage corresponding to the amount of infrared light in accordance with the temperature of the top plate detected by the detecting means; and amplifying means for amplifying the output of the output subtracting means, and depending on the output of the amplifying means The control means is the An induction cooking device for controlling the heating power to the heat coil,
The amplification means has a switching means for switching the amplification factor, and the control means has an automatic cooking sequence, and in the heating mode in which the fried food is performed, the temperature change of the heated object up to 350 ° C. In the automatic cooking sequence in which the amplification factor is set so that it can be detected and the cooking menu for boiling or cooking is performed, the amplification factor is switched to a lower value than in the heating mode to control the temperature of the automatic cooking sequence. An induction heating cooker characterized by that.

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